package org.opsli.core.utils;

//CGS2000转WGS84
public class CGS2000Util {

    private static double formatby6(double num) {
        String result = String.format("%.6f", num);
        return Double.valueOf(result);
    }

    //2000转84
    public static double[] CGS2000ToWGS84(double X, double Y) {

        double L0 = 117;//中央子午线需根据实际情况设置
        double lat ,lon;
        Y-=500000;
        double []  result  = new double[2];
        double iPI = 0.0174532925199433;//pi/180
        double a = 6378137.0; //长半轴 m
        double b = 6356752.31414; //短半轴 m
        double f = 1/298.257222101;//扁率 a-b/a
        double e = 0.0818191910428; //第一偏心率 Math.sqrt(5)
        double ee = Math.sqrt(a*a-b*b)/b; //第二偏心率
        double bf = 0; //底点纬度
        double a0 = 1+(3*e*e/4) + (45*e*e*e*e/64) + (175*e*e*e*e*e*e/256) + (11025*e*e*e*e*e*e*e*e/16384) + (43659*e*e*e*e*e*e*e*e*e*e/65536);
        double b0 = X/(a*(1-e*e)*a0);
        double c1 = 3*e*e/8 +3*e*e*e*e/16 + 213*e*e*e*e*e*e/2048 + 255*e*e*e*e*e*e*e*e/4096;
        double c2 = 21*e*e*e*e/256 + 21*e*e*e*e*e*e/256 + 533*e*e*e*e*e*e*e*e/8192;
        double c3 = 151*e*e*e*e*e*e*e*e/6144 + 151*e*e*e*e*e*e*e*e/4096;
        double c4 = 1097*e*e*e*e*e*e*e*e/131072;
        bf = b0 + c1*Math.sin(2*b0) + c2*Math.sin(4*b0) +c3*Math.sin(6*b0) + c4*Math.sin(8*b0); // bf =b0+c1*sin2b0 + c2*sin4b0 + c3*sin6b0 +c4*sin8b0 +...
        double tf = Math.tan(bf);
        double n2 = ee*ee*Math.cos(bf)*Math.cos(bf); //第二偏心率平方成bf余弦平方
        double c = a*a/b;
        double v=Math.sqrt(1+ ee*ee*Math.cos(bf)*Math.cos(bf));
        double mf = c/(v*v*v); //子午圈半径
        double nf = c/v;//卯酉圈半径

        //纬度计算
        lat=bf-(tf/(2*mf)*Y)*(Y/nf) * (1-1/12*(5+3*tf*tf+n2-9*n2*tf*tf)*(Y*Y/(nf*nf))+1/360*(61+90*tf*tf+45*tf*tf*tf*tf)*(Y*Y*Y*Y/(nf*nf*nf*nf)));
        //经度偏差
        lon=1/(nf*Math.cos(bf))*Y -(1/(6*nf*nf*nf*Math.cos(bf)))*(1+2*tf*tf +n2)*Y*Y*Y + (1/(120*nf*nf*nf*nf*nf*Math.cos(bf)))*(5+28*tf*tf+24*tf*tf*tf*tf)*Y*Y*Y*Y*Y;
        result[0] =formatby6(lat/iPI);
        result[1] =formatby6(L0+lon/iPI);
        //System.out.println(result[1]+","+result[0]);
//        pt = new Point(result[1],result[0]);
        double[] pt =new double[2];
        pt[0]=result[1];
        pt[1]=result[0];
        return pt;
    }
}
